1. Field of the Invention
The present invention relates to a multi-layered semiconductor device and a method for producing the same.
2. Description of the Related Art
Various types of packages have been known in the prior art. On these packages are mounted semiconductor elements such as LSI chips and resin-shielded packages of a non-airtight type have been widely used in the market for economical and mass-production reasons. Typical examples of such a non-airtight type resin-shielded package are, for example, a plastic package and a TCP (tape carrier package). Particularly, the TCP has increasingly been used since it satisfies the recent demands on the semiconductor device and has a large number of pins, a reduced lead pitch, is thin and reduces the size of the device.
More specifically, TCP is a tape carrier type package incorporating a TAB mounting system. A wire-bonding method using minute wires of gold or aluminum for connecting the semiconductor chip to leads of the package has widely been adopted in the conventional semiconductor device. Contrary to this, TCP uses, instead of the wires, copper leads formed on a resinous film (tape). The copper leads can be formed in such a manner that, after a sheet-like adhesive is bonded to the resinous film, the film is punched with a die to form openings at a predetermined pattern and a copper foil is adhered on the film, after which unnecessary part of the copper foil is removed by an etching process. Then, the semiconductor chip is located in correspondence to the opening, and bumps (for example, of gold) formed on electrodes of the chip are bonded to the copper leads on the tape by a suitable jig to result in the target semiconductor device.
It is also desirable to provide a semiconductor package and a semiconductor device capable of producing a high-density module at a low cost and of improving a chip characteristic by minimizing the absolute distance between the chips.
FIG. 7 is a perspective view of a semiconductor device after the semiconductor chip has been connected to the leads of TCP, prior to severing the respective TCP from the tape. TCP 30 uses a resinous film (such as a polyimide resinous film) 31 as a substrate on which are formed leads 32 by etching a copper foil. On opposite sides of the resinous film 31, a plurality of sprocket holes 33 are provided for feeding the film when the assembly of the semiconductor device is sequentially carried out. In addition, as illustrated, an opening 35 (generally referred to as a “device hole”) for accommodating a semiconductor chip 34 is provided in a middle portion of the resinous film 31.
The connection of the semiconductor chip with the leads of the package will be readily understood after reference to FIG. 8 which is an enlarged sectional view of the middle portion of the semiconductor device shown in FIG. 7. After the semiconductor chip 34 has been located in the device hole 35, tip ends of the respective leads 32 are connected to bumps (in general, gold-plated projections) 36 on individual electrodes of the semiconductor chip. The connection of the leads is generally carried out by a flat bonding method while using a known bonding tool. In this regard, a tip end of the copper lead 32 is plated with gold or tin prior to the bonding process for facilitating the bonding with the bump 36. Finally, although not illustrated in FIG. 7 for the purpose of simplification, an insulation resin 37 is wrapped around both of the semiconductor chip 34 and the leads 36 to shield them from the ambient humidity and contamination. The shielding insulation resin is, for example, an epoxy-type resin.
Recently, it has been desired that the semiconductor device is made smaller and thinner. Also the semiconductor chip itself is desired to be thinner. That is, while a thickness of the conventional semiconductor chip is approximately in a range from 400 to 500 μm, it is preferably in a range from 40 to 50 μm. Although the semiconductor device is preferably as thin as possible, such a thinning, as well as the control thereof, are difficult. Also, if the thickness is reduced, the shielding with resin is difficult to control.
It is also desired in such a semiconductor device or a semiconductor package used therefor that the semiconductor element and the semiconductor package are easily connected to each other at a low cost.
Further, it is also desired to provide a semiconductor package and a semiconductor device capable of producing a high-density module at a low cost and of improving electrical characteristics of elements by reducing an absolute distance between the elements.